Voltage control method for an electric motor control system

Abstract

A method for controlling regenerative energy in a system having an motor and having a power converter for converting regenerative energy from the motor for supply as electrical current to a receiving apparatus includes estimating a resistance to electrical current flow between the electrical power converter and the receiving apparatus and measuring a first voltage at the receiving apparatus. The method further comprises controlling a regenerative current from the power converter to the receiving apparatus in view of the resistance and the first voltage to limit a second voltage at the power converter.

What is claimed is: 
     
       1. A method for controlling regenerative energy in an electrically-propelled vehicle having a motor and having a power converter for converting regenerative energy from said motor for supply to a battery, said method comprising the steps of: (a) estimating a resistance to electrical current flow between said electrical power converter and said battery;   (b) measuring a terminal voltage of said battery;   (c) controlling a regenerative current from said power converter to said battery in view of said resistance and said terminal voltage to limit a voltage at said power converter.   
     
     
       2. A method as recited in claim 1, wherein estimating a resistance to electrical current flow further comprises: measuring a voltage V 1  at said power converter at a first time;   measuring a current I 1  between said power converter and said battery at said first time;   measuring a voltage V 2  at said power converter at a second time;   measuring a current I 2  between said power converter and said battery at said second time; and   calculating said resistance as a difference between V 2  and V 1 , divided by a difference between I 2  and I 1 .   
     
     
       3. A method as recited in claim 2, wherein estimating a resistance further comprises employing an initial resistance estimate at an initial time, said initial estimate representing a nominal internal resistance of said battery as a function of a state of charge of said battery at said initial time. 
     
     
       4. A method as recited in claim 2, wherein estimating a resistance further comprises employing an initial resistance estimate at an initial time, said initial estimate representing a nominal internal resistance of said battery as a function of a temperature of said battery at said initial time. 
     
     
       5. A method as recited in claim 2, wherein estimating a resistance further comprises employing an initial resistance estimate at an initial time, said initial estimate representing a nominal internal resistance of said battery as a function of a state of charge and a temperature of said battery at said initial time. 
     
     
       6. A method as recited in claim 1, wherein said step of controlling a regenerative current comprises limiting said regenerative current to maintain said voltage at said power converter below a predetermined threshold. 
     
     
       7. A method as recited in claim 2, wherein said step of controlling a regenerative current comprises limiting said regenerative current to maintain said voltage at said power converter below a predetermined threshold. 
     
     
       8. A method as recited in claim 5, wherein said step of controlling a regenerative current comprises limiting said regenerative current to maintain said voltage at said power converter below a predetermined threshold. 
     
     
       9. A method for controlling regenerative energy in a system having an motor and having a power converter for converting regenerative energy from said motor for supply as electrical current to a receiving apparatus, said method comprising the steps of: (a) estimating a resistance to electrical current flow between said electrical power converter and said receiving apparatus;   (b) measuring a first voltage at said receiving apparatus;   (c) controlling a regenerative current from said power converter to said receiving apparatus in view of said resistance and said first voltage to limit a second voltage at said power converter.   
     
     
       10. A method as recited in claim 9, wherein estimating a resistance to electrical current flow further comprises: measuring a voltage V 1  at said power converter at a first time;   measuring a current I 1  between said power converter and said receiving apparatus at said first time;   measuring a voltage V 2  at said power converter at a second time;   measuring a current I 2  between said power converter and said receiving apparatus at said second time; and   calculating said resistance as a difference between V 2  and V 1 , divided by a difference between I 2  and I 1 .   
     
     
       11. A method as recited in claim 9, wherein said step of controlling a regenerative current comprises limiting said regenerative current to maintain said voltage at said power converter below a predetermined threshold. 
     
     
       12. A method as recited in claim 10, wherein said step of controlling a regenerative current comprises limiting said regenerative current to maintain said voltage at said power converter below a predetermined threshold.